Method of forming rapidly disintegrating paper tubes

ABSTRACT

A method of forming a tube is disclosed which has the strength and stiffness required for a tampon applicator tube and which can rapidly disintegrate in water. A method including the steps of directing a web of paper, a web of adhesive film and a web of superabsorbent material on to a mandrel. Wrapping said webs on the mandrel to form a laminate, and then heating the laminate to form a seal between the various layers to produce a finished tube.

This is a divisional of co-pending application Ser. No. 032,833 filed onMar. 30, 1987, now U.S. Pat. No. 4,792,326.

FIELD OF THE INVENTION

This invention relates to paper tubes that disintegrate rapidly whenplaced in water. In particular, the invention relates to a method offorming applicators for catamenial tampons that will disintegrate whendisposed of in a toilet and not obstruct plumbing when the toilet isflushed.

BACKGROUND OF THE INVENTION

The catamenial tampon is a compressed cotton or other fibrous materialthat may be contained in a paper tube, plastic tube or mounted on astick prior to use. With a paper tube or plastic tube tampon, theapplicator normally has an inner and outer tube, with the inner tubebeing utilized to eject the tampon into the vagina from the outer tube.It is necessary that the paper tubes be formed stiff and strong enoughfor insertion and injection of the tampons into the vagina. However,when stiff, strong tubes of adhesively wrapped paper are disposed of ina toilet, the tubes will not rapidly disintegrate and are difficult toflush. As they ar difficult to flush, it may lead to jamming of thepipes of the plumbing system.

It has been proposed in U.S. Pat. No. 3,419,005 to Lewing that a wettingagent be added to the tube to aid in the disintegration of the tube. Theaddition of wetting agent is also proposed in United Kingdom Pat. No.1,049,894 to Robinson and Sons Limited, where the combination of anonionic wetting agent and cetyl trimethyl ammonium bromide is proposed.It is also known to load the paper tubes with a mineral filler, such ascalcium carbonate, to aid in the sinking of the tube into the toilet forbetter wetting. The formation of paper tubes may be carried out eitherwith the formation of spiral-wound tubes, such as generally shown inU.S. Pat. No. 3,194,275 to Biggs, Jr., et al. and U.S. Pat. No.3,430,543 to Cunningham. Also, it is known that tampon tubes may beformed by convolutely winding tubes such as disclosed in U.S. Pat. No.4,650,459 to Sheldon and U.S. Pat. No. 4,522,967 Sheldon.

However, there remains a need for a more rapidly disintegrating tube.There particularly remains a need for a tube that may be convolutelywound, is strong, low in cost and rapidly disintegrates.

SUMMARY OF THE INVENTION

An object of the invention is to overcome disadvantages of priordisintegratable tubes and methods of their formation.

A further object of the invention is to produce a rapidly disintegratingtampon tube that will be flushable.

Another additional object is to produce a low-cost method of formingwater-disintegrating tampon tubes.

These and other objects of the invention are generally accomplished byproviding a tampon tube that is formed of a series of layers of paper,adhesive sealing means and super-absorbent material. The method offormation generally is to provide each of these materials in a sheetform and wind the tube convolutely with heat sealing during winding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of apparatus for forming the paper tubeof the invention.

FIG. 2 is a top view of the apparatus and method of FIG. 1.

FIG. 3 is a cross-sectional view of a tube in accordance with theinvention.

FIG. 4 is an enlarged view of the area designated FIG. 4 in FIG. 3.

FIG. 5 is an alternate method and apparatus for forming an alternateembodiment of the tube of the invention.

FIG. 6 is a cross-section of a tube formed by the method of FIG. 5.

FIG. 7 is an enlarged view of the area designated FIG. 7 in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

The disposable tube of the invention has numerous advantages over priortubes. The tube provides very rapid disintegration of the wrapped papertube. Further, the tube has strength and stiffness as required for itsuse. The means used for disintegration of the tube does not interferewith the adhesive connection during forming. These and other advantagesof the invention will be apparent from the detailed description below.The use of heat sealable webs in forming the tubes avoids handling ofsticky liquid glue materials.

A method and apparatus for forming the tube of the invention isillustrated in FIGS. 1 and 2. The tube is wound on mandrel 10. The tubeis wound from four webs. Webs 12 and 14 are heat-sealable films. Web 16is a film of superabsorbent or superabsorbent impregnated carrier web.Web 18 is paper. These tubes are wrapped in layers onto mandrel 10 andsealed together by heated roll 20 bearing against mandrel 10. The websare kept at constant tension during windings by the rolls 22, 24, 26 and28.

The tube 30 illustrated in FIGS. 3 and 4 is composed of two completewindings of the webs of FIG. 1. The webs are held in place by thesealing of the heat-sealable webs 12 and 14. While illustrated with twolayers, it is within the invention to wind more layers depending on thestiffness of the paper and the stiffness of the tube required to beformed.

In FIG. 5 there is illustrated an alternate embodiment of the invention.As illustrated in FIG. 5, the tube of the invention is composed of threelayers of webs. Web 34 is a heat-sealable web. Web 36 is asuperabsorbent web that is perforated by apparatus 38. Web 40 is paper.The webs are wound on mandrel 42 and fused by heating roll 44 bearingagainst the mandrel 42. Roll 46 is the backup roll for perforator 38.

FIGS. 6 and 7 illustrate a disposable tube made utilizing the alternateprocess of FIG. 5. As illustrated in FIGS. 6 and 7, the tube 50 hasthree thicknesses of webs 34, 36 and 40. The adhesive layer 34 haspassed through the perforations 52 and joined the paper layers 40directly together through the perforations of superabsorbent layer 36.

The paper utilized in forming the tubes of the invention may be any typethat provides a tube of suitable properties of stiffness and cost.Generally, catamenial tubes are formed of a paper commonly referred toas groundwood base sheet. A preferred material is the 30 lb. free sheetof ground wood that has been provided with a slippery coating of highclay content. This material is preferred as the coating is slippery forease of insertion and aids in disintegration and sinking of the tube asit is fast wetting. Further, the material is low in cost.

The adhesive web may be any of several known adhesive webs that willseal at temperatures that do not degrade the paper or the superabsorbentmaterial. The adhesive may be any heat-sealable material that is capableof bonding at temperatures that do not degrade the paper or cardboardutilized. Typical of such materials are meltblown webs of polypropyleneor polyethylene. One such material is a Sharnet™ web of either polyesteror polyamide resin composition. In one particularly preferred form ofthe invention, the adhesive may be a heat sealable and water solubleadhesive. The water soluble adhesive, combined with a superabsorbent,creates a particularly preferred material.

The superabsorbent sheet of the invention may be any suitable materialthat will quickly absorb water and swell, leading to disintegration ofthe tube. One advantage of the superabsorbent materials is that whenthey absorb water, they swell by a great amount, forcing the tube apart.As the tube is forced apart by swelling, more and more of thesuperabsorbent is exposed. Further, the swelling tends to break down theintegrity of the tube, aiding in its being flushed. The webs of thesuperabsorbent of the invention may be other continuous webs ofsuperabsorbent material or they may be material such as tissue carriersheets that have been impregnated with a superabsorbent or laminatedwith powdered superabsorbent. Such materials are known in the art andgenerally are hydrogel materials that have the ability to absorb waterbut are crosslinked so as to not be water soluble. Such film materialsare disclosed in U.S. Pat. No. 4,186,238 to Holst et al., U.S. Pat. No.4,117,184 to Erickson et al., U.S. Pat. No. 2,192,827 to Mueller, U.S.Pat. No. 4,212,036 to Pedersen, U.S. Pat. No. 4,176,667 to Herring, U.S.Pat. No. 4,592,751 to Gegelys and U.S. Pat. No. 4,144,886 to Holst etal.

The term superabsorbent as used herein is intended to mean the synthetichydrogel polymers. Such hydrogel polymers include, for example,carboxymethylcellulose, alkali metal salts of polyacrylic acids,polyacrylamides, polyvinyl alcohol, ethylene maleic anhydridecopolymers, polyvinyl ethers, hydroxypropyl cellulose, polyvinylmorpholinone, polymers and copolymers of vinyl sulfonic acid,polyacrylates, polyacrylamides, polyvinyl pyridine and the like. Othersuitable polymers include hydrolyzed acrylonitrile grafted starch,acrylic acid grafted starch, and isobutylene maleic anhydridecopolymers, and mixtures thereof. The hydrogel polymers are preferablylightly cross-linked to render the materials substantially waterinsoluble. Cross-linking may, for example, be by irradiation or bycovalent, ionic, Van der Waals, or hydrogen bonding. Suitable materialsare available from various commercial vendors, such as Dow ChemicalCompany, Celanese Corporation, Allied-Colloid, and Stockhausen. Thesuperabsorbent hydrogel material utilized in the invention is capable ofabsorbing at least about 15 times its weight in water, and preferably iscapable of absorbing at least about 25-100 times its weight in water.

The following examples are intended to be illustrative and notexhaustive of the practice of the invention.

EXAMPLE I

A 3"×6" sheet of 30 lb. paper and a 3"×6" sheet of superabsorbent filminterleaved with two 3"×6" sheets of Sharnet™ polyester adhesive areconvolutely wound into a tube. The paper is a relatively inexpensivegrade from Midtec Paper, containing a high percentage of groundwood. Thesuperabsorbent layer is commercially available film manufactured by DowChemical. The film is an acrylic absorbent film laminated between sheetsof lightweight tissue with a dry weight of about 73 g/m². The adhesiveis a commercially available heat sealable fibrous adhesive web fromSharnet Corp.

The sheets are convolutely wound on a Teflon-coated mandrel to form atampon tube of 0.640" I.D. and 3" in length. The tube is sealed byrolling the mandrel on a hot plate at 400° F. for approximately 10seconds as the tube is formed. The tube is then cooled to ambienttemperature and dropped into a beaker of water. Initial delaminationoccurs in 5 minutes and total delamination time is 10 minutes.

EXAMPLE II

The procedure of Example I is repeated except a sheet of heat sealable,water soluble polyethyloxazoline adhesive of a composition as disclosedin U.S. Pat. No. 4,522,967 to Sheldon et al. is substituted for thepolyester adhesive. This use of a water soluble adhesive, in addition tothe superabsorbent layer, results in an even faster delamination thanthe tube of Example I.

While the invention has been directed primarily to the formation ofcatamenial tampon tubes, it is also suitable for use in making othermaterials where rapid disintegration in water would be desirable. Forinstance, it could be utilized in the forming of toilet paper tubes ortubes that would be utilized on ships where waste is disposed ofoverboard. These and other products are intended to be included by theinvention, the scope of which is to be limited only by the claimsattached hereto.

We claim:
 1. A method of forming a wound tube which has the strength andstiffness required for a tampon applicator tube and which can rapidlydisintegrate in water, said method comprising the steps of:(a) directingat least one web of paper, at least one web of an adhesive film and atleast one web of a super-absorbent material in a predetermined fashiontowards a mandrel; (b) wrapping said webs on said mandrel to form alaminate; (c) heating said laminate under pressure to form a sealbetween said webs and produce a finished tube; and (d) removing saidfinished tube for said mandrel.
 2. The method of claim 1 wherein saidwebs ar kept at constant tension during wrapping on said mandrel.
 3. Themethod of claim 1 wherein said adhesive film is a heat sealablepolyester.
 4. The method of claim 1 wherein said adhesive film is a heatsealable, water soluble polythyloxayoline.
 5. A method of forming awound tube which has a predetermined strength and stiffness and whichcan rapidly disintegrate in water, said method comprising the stepsof:(a) directing a plurality of webs towards a mandrel, said websincluding a web of superabsorbent material positioned between two websof adhesive film and a web of paper positioned adjacent to one of saidadhesive films; (b) wrapping said webs on said mandrel to form alaminate; and (c) heating said laminate to form a seal between said websand produce a finished tube.
 6. The method of claim 5 wherein saidlaminate is heated under pressure.
 7. The method of claim 5 wherein saidwebs are kept at constant tension during wrapping on said mandrel. 8.The method of forming a wound tube which has a predetermined strengthand stiffness and which can rapidly disintegrate in water, said methodcomprising the steps of:(a) directing a web of superabsorbent materialpositioned between a web of adhesive film and a web of paper toward amandrel; (b) perforating said web of superabsorbent material upstream ofsaid mandrel; (c) wrapping said webs on said mandrel to form a laminate;and (d) heating said laminate under pressure to form a seal between saidwebs, said adhesive film passing through said perforations and directlyadhering to said paper to form a finished tube.
 9. The method of claim 8wherein said webs are kept at constant tension during wrapping on saidmandrel.
 10. The method of claim 8 wherein said webs are convolutelywound onto said mandrel.
 11. The method of claim 8 wherein saidperforations are formed by a roll having a plurality of pins extendingoutward from the circumference thereof, said pins being brought intocontact with said web of adhesive film.
 12. A method of forming a cubecomprising providing at least one web of paper, at least one webcomprising an adhesive film and at least one layer comprising asuperabsorbent material, wrapping the webs on a mandrel, and heating toseal said webs together to form a tube.
 13. The method of claim 12wherein said superabsorbent material comprises a cellulose web carryinga superabsorbent.
 14. The method of claim 12 wherein said superabsorbentweb is perforated.
 15. The method of claim 12 wherein there are two websof thermoplastic film in combination with one web of paper and one webof superabsorbent
 16. The method of claim 12 wherein said tube is atampon applicator.
 17. The method of claim 12 wherein said tube isconvolutely wound.
 18. The method of claim 12 wherein said tube isspirally wound.
 19. The method of claim 12 wherein said superabsorbentmaterial comprises a film of superabsorbent.
 20. The method of claim 12wherein said adhesive comprises a heat setting water soluble material.